Treating hydrocarbon oils



Dec. l0, 1935. G. o. sHEFsTEAD TREATING HYDROCARBON OILS Filed Feb. lO, 1928 Patented Dec. l0, 1935 UNITED STATES TREATING HYDROCARBON OILS Guy O. Shefstead, Craig, Colo., assigner to The Texas Company, New York, N. Y., a corporation of Delaware Application February 10, 1928, Serial No. 253,264

12 Claims.

wherein crude petroleum is stripped of its natural gasoline or naphtha content, the resultant crude residuum subjected to cracking for the production of lower boiling products, and the tar or residue produced in the cracking operation subjected to vaporization to recover therefrom any gasoline or other light products contained therein and also to recover a. distillate suitable for use in the cracking operation.

My invention contemplates a process wherein a liquid or condensate from a dephlegmator or iractionating column employed in d-ephlegmating or rectifying the evolved vapors formed in the cracking Zone, is expanded into a distilling apparatus wherein a crude charge is stripped of its gasoline or naphtha content. In practicing the invention crude petroleum or other oil containing gasoline or naphtha fractions is conducted to a 30 distilling apparatus in which the natural gasoline or naphtha content or other fractions desired are distilled oit and the stripped crude is introduced Ato a cracking Zone maintained under superatrnospheric pressure. The evolved vapors while preferably still under superatmospheric pressure are subjected to dephlegmation or fractionation, the desired gasoline or naphtha distillate being taken ofi and the reflux condensate comprising essentially heavier constituents is directed to the crude stripping apparatus, preferably into a fractionating or dephlegmating tower included in such apparatus. The crude stripping apparatus is preferably operated at substantially atmospheric pressure and the cracking operation including the dephlegmation or fractionation of the evolved vapors from the cracking zone carried on under high pressure, such for example as several hundred pounds pressure, so that no pump is required to transfer the hot liquid from the pressure dephlegmator to the crude stripping equipment, the pressure differential being utilized to force the condensate from the pressure dephlegmator into the crude stripping apparatus. The hot liquid from the pressure dephlegmator supplies additional heat for the crude stripping operation and furthermore the condensate from the pressure dephlegmator is stripped of its gasoline or naphtha content. In present systems of operation wherein the fractionation or dephlegmation of the evolved vapors from a cracking zone is carried on under pressure, the reflux condensate invariably contains greater or less amounts of gasoline or naphtha, and when this reflux condensate is brought back into the cracking zone the presence of the light constit. 10 uents contained in the condensate increases the pressure that has to be carried on the pressure cracking apparatus. In accordance with my invention the reiiux condensate is efficiently stripped of its gasoline or naphtha content by being 15 expanded into a low pressure distilling system. The stripped crude, together with the stripped reflux condensate that has been drawn from the pressure dephlegmator, is then passed into the cracking zone. 20

Another process contemplated by the invention involvesrthe production of pressure still residue, the distillation of this residue at reduced pressure, and the introduction of a distillate obtained from this distillation to a crude stripping apparatus arranged to remove volatile constituents from the charge to the pressure still. Thus the tar or residue stripping equipment may operate without any material fractionation of the evolved vapors, and these vapors may be condensed and the condensate introduced into a fractionating or rectifying tower which operates on the vapors evolved in distilling the initial crude oil charge.

Another process contemplated by the invention involves condensing under pressure the evolved vapors of the pressure still, and the introduction of condensate thus obtained to a fractioning to'wer operating to rectify the evolved vapors produced in vaporizing the initial crude charge, 40 or this condensate may be introduced to a fractionating tower operating on the evolved vapors obtained in distilling the tar or residue from the pressure still, so as to thus in either case avoid the necessity of using pumps for introducing a reflux medium to the towers, and to thus introduce the condensate from the high pressure condenser directly into a low pressure rectifying column.

Theinvention also has in view the provision of a heating coil for heating the initial crude charge,

a vaporizing chamber into which this coil discharges, a second coil which is adapted to raise to a cracking temperature an oil charge which may include the residue obtained from the vaporizing chamber employed in treating the initial crude charge, a drum or still adapted to receive the oil from the second coil in which still the oil may be maintained at a cracking temperature for a time sufficient for the desired molecular transformation, Van expansion or vaporizing chamber in which tar orV residue drawn from the pressure tstill is .distilled to free .it of its gasoline or naptha content and also torproduce distillates for cyclic retum to the crackingzone, a dephlegmator for treating the evolved vapors from .the cracking still and means for directing condensate from the dephlegmator into the kdis'tiflling equipment for Vthe initial crude charge.

The invention furthermore V`contemplates the provision of suitable process and apparatus `adapted for commercial operation o`n a large scale whereby crude oil is charged to the system, distilledv to free it of its naturalV gasoline Yor naptha content, the residue thus obtained subjected to cracking for-the production of -`further quantities of gasoline, the Yresidue obtained from the cracking Voperation distilled l.under reduced pressure to' recover gasoline therefrom -and to form heavier distillates, the evolvedvaporsfof the cracking opration dephlegmated or rectified and the reflux condensate thus fformed directed -into the crude oil distilling equipment, and the residue from the crude distilling equipment together with the stripped reilux condensate obtained from the dephlegmation of "the vapors from the cracking` Azo'ne and Ywith 'distillates obtained from the distillation of the residue from the cracking zone, is introduced into the cracking Zone.

The invention also has in View the provision of various modifications described hereinafter inv volvingvarious elements and assemblies o'f elements and various methods of operation as more completely set forthY hereinafter.

In` order to more fully disclose 'the invention reference will now be had to the accompanying drawing which is a flow diagram of an apparatus constructed in accordance Awith the invention and constituting anembodimentfthereof.V Y Y In the apparatus thus illustrated a pump ID servesto introduce the charging stock, `such `as crude petroleum or other o'il containing gasoline or naphtha constituents, through a c'harginglline I Iinto a heating coil I 2. Thelatter coil is shown located in an economizer section or lowerjtemperature portion ofV a vfurnace `-I3. The -coil I2 communicates with a'trans'fer line I4 `by which the heated oil is removed from the coil Aand discharged into a vaporizing chamber `I5. Y Baiiles i5 are indicated in the chamber I5 for assisting in the separation of thevapors from V.the Vliquid portions of the oil. The still I5 is provided with a fractionating or rectifying'towereI'I. A vapor line I 8 conducts vapors rom'the still I5 to the fractionating 'tower I'Iand areflux condensate line I9. conducts liquidV from the ktower I"I back to the vaporizing chamber I5. VIn some .cases the vaporizing orstripping chamber I5 andthe fractionating tower 'I'I maybe constructed as asingle char'nbentheV hot crude charge being introducedY -into a lower and preferably .abaflled section ofi-.a column `still Ywlfiile.fractionation vof thervapors and vconduct them .to acondenser ,'22 having supplied by the coil 2li. 'w'itht'wo branch lines [i3 and dfi, the line I3 con- V.pressure tower I 'I.

outlet pipe 23 by which the gasoline or naphtha fraction is discharged from the condenser.

Y 'I'he stripped crude is removed from the still I5 and by means of a pipe 24, is conducted to a pump 25 which forces the oil through a pipe 26 into a 5 coil 2'I which is located in the furnace I3. A burner 28 is indicated for supplying heat to the furnacapand .the arrangement is such that the oil in transit 'through the coil 2l may be raised to a cracking temperature under superatmospheric Ipressure. It is to be understood that the coil I2 'is in a lower temperature section of the furnace I3 and does not receive the high temperature ap- Yplied to .the coil 2l.V An auxiliary burner 2S is indicated `for supplying additional heat to the coil 15 I2 incase v'the waste gases that have been employed in heating the coil 2 are inadequate for raising the temperature of the oil in the co-il I2 to thedesired degree. A transfer line 33 conducts the oil which'has been heated to a cracking mm- 'perature :in the coil xEl toa still or converter 3l vwherein the oil is Ysubjected to cracking or decomposition for the vproduction of lower boiling 'point products. If desired aplurality of stills or converters `may be employed in "lieu of the single 25 still shown in the drawing. Avapor line 32 conducts evolved vapors 'from the `still to a fractionating .or :rectifying tower 33. The tower is shown equipped with a coil 33 for supplying cooling thereto, and a v.vapor line '35 -'conducts the Vapor-fraction to a condenser coil 36 having an outlet pipe 3?! communicating with -a receiving drum 38. Thereceiving drum vis preferably maintained under superatmospheric :pressure although the pressure in the drum may be reduced from that obtaining in the condenser 35. A pipe 33 conducts the cracked gasoline or naphtha distillate to a tank 40. The condensate separated out in 'the fractionating column 33 is removed by a valved line 4I and introduced into the tower il. 40 Aline 42 ris shown for introducing a gasoline or'naphtha distillate to serve as a reflux medium for the 'tower II, 'the liquid thus introduced being employed either in addition to the cooling supplied by the vcoil '25J or in lieu of the cooling 45 'The pipe 42 is shown necting with the pipe 3? at a point therein before 'the pressure has been reduced by the valve indi- `cated in theline 3l and the pipe 44 extending to the line '39, Vso that condensate may be drawn either from the outlet from the coil 33 or from the outlet of thereceiving drum 33 and the pres- ;sure on the condenser coil 35 or'in the receiving Vdrum 33 utilized to force the liquid into the lower 55 The pipe 5.12 is also shown Vwith a branch 'linelz'i'extending to a pump 45 Whichhas a discharge line il terminating in the upper part Yof the Vfracticnating tower 33 so that rif desired condensate either from the coil 36 or from the 'receiving drum .'38 may be introduced into the 'top of the tower 33 to serve as a reiiux medium` therein. The Ycooling supplied in this Ymanner may be used either fin addition to that `,furnished by the coil 3L. or in lieu of the cooling 65 Vsupplied by the coil 34. The outlet 23 of the cooling coil '22 isrshown extending to the tank 5,8 so that 'the gasoline or naphtha distillate obtained from the condenser l2 may be combined with that Yobtained from' the condenser coil 36, al- 70 Y'thoughvif desired separate receiving or storage tanks may be provided.

'The tar or residue formed in the pressure 'crackingstill 3| is withdrawn through a line llc vhaving :a ypressure vreducing valve 4S and the 75 residue is discharged into a distilling chamber 50 which is maintained under reduced pressure preferably approximately atmospheric pressure. 'I'he still 5i] is preferably insulated and ordinarily requires no heat othe-r than that furnished by the hot incoming oil, andunder the reduced pressure vapors are given of which are removed through a vapor line iii to a condenser coil 52 and the condensate passes thence into a receiving tank 53. This condensa-te may be referred to as a light gas oil stock and if desired it may be introduced into the pressure cracking system or more specically it may be charged into thecoil 2 to be commingled therein with the residue received from the still i5. The distiiiate collected in the tank 53 however, ordinarily contains more or less gasoline or naphtha constituents and therefore it is preferable to conduct this distillate to the crude stripping apparatus in order that the lighter constituents may b-e removed. Accordingly a pump 5d is provided having a connection 55 to the tank 53 and having a discharge line 55 which terminates at a midpoint in the tower l'i. Thus the uniractionated distillate obtained from the still "d is freed of its gasoline or naphtha content and combined with the stripped crude being introduced to the coil Ei' and cracking still 3|.

The residue from the still 5!) is withdrawn through a line 5l into a second still 58. This still is supplied with a line 59 by which steam preferably superheated is introduced into the still. t is convenient to operate the still 5i) at a pressure slightly above atmospheric, such for example as about ten pounds, and maintain the still 5B at substantially atmospheric pressure, so that residue from the still may be readily discharged into the still 58. Vapors from the still 55 pass through a vapor line 50 into a condenser coil 5i and the condensate is collected in This condensate ordinarily contains um proportions if any of the gasoline or `vna fractions and consequently this distilinay be introduced directly into the pressure cracking system, A pump 63 is provided having a line Sii communicating with the tank having a discharge line 65 which extends to the coil il'l or more specically which connects with pipe 25. The distillate collected in the tank 52 may be designated a heavy gas oil. This distiliate is thus combined with the stripped crude and reiiux condensates obtained in the crude stripping apparatus. The stripped residue from the still 58 which may be termed fuel oil is drawn through a line 55, passed through a cooling coil Si, and admitted to a tank G3.

in practicing the invention crude petroleum or other oil containing light constituents, such as gasoline, is passed through the coil l2 wherein it is brought to the desired vaporizing temperature. The heated oil is discharged into the vaporizing chamber i5 which as stated is maintained under approximately atmospheric pressure so that separation of the lighter constituents from the heavier takes place readily. The vapors are drawn oit through the vapor line i3 into the rectifying or rractionating column il and a gasoline condensate is obtained in Ythe condenser 22. If desired the cil may be heated suiciently in the coil i2 to take oii in addition to a gasoline fraction heavier distillates, such for example as kerosene, and the iractionating equipment may be so designed as to take oii gasoline and kerosene fractions. The stripped residue is drawn off from the vaporizing chamber l5 and forced by the pump '25 through the coil 2i wherein the oil is brought to a cracking temperature. The oil is then discharged into the cracking still 3| where cracking conditions are maintained. The vapors are fractionated in the column 33 while still under superatmospheric pressure preferably at substantially the pressure of the still 3l. An overhead vapor fraction is taken off through the vapor line 35, condensed in the condenser 36 and passed to the receiver 38 from which it may be discharged into the tank 4G.

Due to the high pressure at which fractionation takes place in the chamber 33 which may for example be several hundred pounds, the reflux condensate collected at the bottom of the chamber contains greater or less proportions of gasoline constituents. This condensate is discharged through a pressure reducing valve in the line il and introduced into the tower Il so that the gasoline or other light constituents may be removed and the stripped condensate combined with the other liquid in the tower. rlhe liquid is refluxed 20 quantities of gasoline and may also contain other 30 heavier constituents -such fractions of the gas oil type. This condensate is passed through the line 5E and introduced to the ractionating column il so that the gasoline or lighter constituents may be removed and the heavier portions combined with the redux condensate that ultimately forms a part of the charging stock to the cracking zone. The heavier distillate obtained from the still 53 should be rela-tively free of gasoline and this distillate may be passed through the line 55 and thus introduced directly into the stream of oil entering the heating coil 2l. The residue stripping apparatus may thus be operated without any fractionating or rectifying towers and yet by introducing distillate obtained therefrom into the tower il all of the gasoliney constituents may be recovered, while at the same time the heavier constituents in the distillate are adequately utilized as part of the charging stock to the cracking zone.

The receiver 38 in which the cracked gasoline or naphtha distillate is collected is ordinarily held at superatmospheric pressure but at a pressure reduced from that obtaining in the condenser and thus a portion of the distillate may be drawn 01T either through the line i3 or 44 and the pressure diierential utilized to force the distillate through the line 42 and into the low pressure fractionating chamber i 7 to serve as a redux medium therein.

In one modification of the invention additional heating may be supplied to the oil to be distilled in the stripping still I5 by bringing hot products from a higher temperature portion of the system into contact with the products to be distilled. Thus a valved line t@ may be provided connecting the transfer line Sil with the line I 4 so that a portion of the highly heated oil leaving the coil 2l may be directed into the line i4. In this way the oil leaving the coil l2 may be brought to the distilling temperature desired either with or without the aid of the auxiliary heating means 29. Another way of accomplishing the same result may be eiiected by directing a portion of the hot reflux condensate from the A fractionating tower 33 `into the line I4, as by to thus combine the condensate with the stripped Y residue received from the still i5 for passage through the heating coil 2l. The passage of the heated oil from the higher temperature and pressure zone into the lower temperature and pressure zone may be carried on continuously or it may be intermittently employed to meet emergency conditions. Y

Other rmodifications may be effected-within the'spirit and scope of my invention, and I desire no limitation other than those imposed by the appended claims.

What I claim is: Y

1. The process of treating hydrocarbon oils that comprises passing a charging stock containing low boiling constituents through a heating coil to thereby heat the oil to a temperature suicient to vaporize a given fraction, discharging the heated oil into an enlarged chamber wherein va- Y porization takes place under substantially atmospheric pressure, passing'the vapors to a low pressure iractionating column and Ysubjecting them to the fractionation therein, removing from the enlarged chamber the oil thus stripped of its light- Y removing vapors and residue `from the cracking chamber, subjecting the vapors to fractionation to form a vapor fraction and a reilux condensate, condensing the vapor fraction, releasing the reilux condensate into the low pressure fractionating columnto thereby strip the condensate of its Vlower boiling constituents and toY combine the condensate withl the other liquid inthe fractionatingV column, distilling the. residu-e withdrawn from the cracking still under reduced pressure to thereby forma lighter and a `heavier distillate, introducingrthe lighterY distillate into the low pressure ractionating column to therebyrrelease 10W- Ver boiling constituents and to combine the heavier portion of the distillate with the other liquid in the fraetionating column, withdrawing the combined liquid from the column, and combining the heavier distilla with the chargebeing introduced to the high temperature heating coil in which the oil is raised to a cracking temperature.A

2. The process of treating hydrocarbon oils that comprises passing a charging stock containf' Aenlarged, chamber the oil thus stripped of its lighter constituents and.. passing the oilunder superlatmospheric pressure through a coil wherein the oil is heatedvto a cracking temperature, Vdischarging the oilinto an enlarged chamber maintained at cracking temperature vunder superatmos'pheric pressure wherein' conversionof higher boiling oilsV takes place, removing vapors and residue 4from the cracking chamber, subjecting the vapors to fractionation to form a vapor fraction and a reflux condensate, condensing the vapor fraction, releasing the reflux condensate into the low pres- 5 Vsure fractionating column to thereby strip the condensate of its lower boiling constituents and to Ycombine the stripped condensate with the liquid in said fractionating column, withdrawing the combined liquid from said column, distilling the l0 residue withdrawn from the cracking still under reduced pressure to thereby form a volatile fraction and a heavier distillate, and combining the heavier distillate with the charge being introduced to the high temperature heating coil in which the I5 oil is raised to a cracking temperature.

3. The process of treating hydrocarbon oils that comprises passing charging stock through a heating coil, passing the heated oil into a vaporizing chamber maintained at relatively vlow pressure, 20 removing residue from the low pressure Vaporizing chamber and flowing it in a restricted stream while heating it to a cracking temperature under a relatively high pressure, discharging the said heated stream of oil directly into an enlarged re- 25 action Zone and diverting a portion ofthe highly heated stream of oil prior to its discharge into the said reaction zone and passing the said diverted oil directly into contact with the charging stock received from the said heating coil to there- 30 by raise the temperature of the oil passing into the said low pressure vaporizing chamber.

4. The process of Vtreating hydrocarbon oils that comprises maintaining oil at cracking temperaturesunder superatrnospheric pressure to effect 35 conversion of higher boiling hydrocarbons into lower boiling ones, introducing an oil containing low-boiling constituents into a distilling apparatus comprising a rst fractionating zone; which is maintained under a materially lower pressure 40 than said iirst mentioned cracking pressure to thereby distill oit a low-boiling fraction, passing the residue thus obtained as charging stock to the high-pressure cracking zone, separating resulting cracked products into vapors and residue, dephleg- 45 mating the vapors in a second fractionating zone at a pressure materially higher than the pressure maintained in the said distilling apparatus and Y rst fractionatingzone to thereby obtain an overhead vapor fraction and a'reflux condensate, sub- 50 jecting the residue from the cracking zone to distillation under a materially reduced pressure by its contained Vheat without further cracking to thereby obtain a distillate containing low-boiling constituents, introducing reflux condensate ob- 55 tained in dephlegmating the cracked vapors and distillate obtained in distilling the residue from the cracking zone into the iirst-named low-pressure distilling apparatus to'thereby distill 01T lowboiling constituents, combining resulting unva- 60 porized portions of said distillate and said reflux condensate with the liquid being introduced into the cracking zone, and condensing the overhead vapor fraction from said'second fractionating zone obtained in dephlegmating the vapors from the cracking zone.

5. The process of treating hydrocarbon oils that comprises maintaining oil at cracking teniperatures under superatrnospheric pressure to effect conversion of higherboiling hydrocarbons into lower boiling ones, introducing an oil containing low-boilingY constituents into a distilling Yapparatus which is under materially lower pressure than the cracking Zone to thereby dis- Vtill 01T a low-boilingV fraction, passing the resi- 75 due thus obtained as charging stock to the high-pressure cracking Zone, separately removing residue and vapors from the cracking zone, deplegmating the vapors in a separate zone while still maintaining them under a pressure materially higher than the pressure in said distilling apparatus to thereby obtain an overhead,

vapor fraction and a reux condensate, subjecting the residue from the cracking zone to distillation to thereby obtain a lighter distillate and a heavier distillate, introducing the light distillate and the reflux condensate obtained in dephleginating the vapors from the cracking zone into the rst-named low-pressure distilling apparatus to thereby distill off low-boiling constituents from said reflux condensate and lighter distillate and to combine the heavy portions of these liquids with the oil being introduced to the cracking Zone, passing' said heavier distillate directly to the oil being introduced to the cracking zone, and condensing the overhead vapor fraction obtained in depnlegmating the vapors from the cracking zone.

6. A process of treating liquids containing high and low boiling hydrocarbons which comprises fractionally distilling said liquid in a zone under relatively low pressure to separate certain of said low boiling hydrocarbons, subjecting the liquid stripped of said lower boiling constituents to materially greater pressure and to a temperature sufficient to eect conversion of at least a portion of said higher boiling hydrocarbons into lower boiling hydrocarbons, maintaining said liquid at said greater pressure and ternerature to effect said conversion and to Vaporize a portion of the liquid so treated, fractionating the last named vapors in a zone separate from the first named fractional distillation Zone at materially greater pressure than that maintained in the said rst named fractional distillation zone, removing lower boiling vapors from the high pressure fractionating Zone and collecting them, refractionating the condensate produced in said high pressure fractionating zone in the first mentioned fractional distillation Zone, passing residual liquid resulting from said conversion directly into a separate unheated distilling Zone of reduced pressure Without further cracking and therein separating a lighter fraction from the residual liquid, fractionating said last named lighter fraction in said rst named fractional distillation Zone, removing low boiling point vapors from said fractional distillation zone and liquefying and collecting the desired fraction therefrom, and passing to the said pressure conversion operation the reflux condensates and unvaporized liquids resulting in the said fractional distillation Zone from the lighter fraction of the residual liquid and from the high pressure fractionated condensate together with the first named stripped liquid.

'7. A process of treating oils containing high boiling hydrocarbons which comprises subjecting oil stock to relatively high pressure and to a temperature sufcient to effect conversion of at least a portion of said higher boiling hydrocarbons into lower bo-iling hydrocarbons, maintaining said oil at said temperature and pressure to effect said conversion and to vaporize a portion of said liquid, fractionating the resulting vapors at relatively high pressure to condense a portion of said vapors, liqueiying and collecting the desired fraction of the remaining vapors, refractionating the condensate resulting from said first mentioned fractionation in a separate Zone at materially reduced pressure, vaporizing a portion of the residual liquid resulting from said conversion at reduced pressure in a separate dis,- tilling zone without further cracking thereof, 5 fractionating the last named portion in said separate refractionating Zone, preheating fresh relatively heavy charging stock and introducing it into said separate refractionating zone, condensing vapors issuing from said separate frac- 10 tionating zone to remove the desired fraction therefrom and collecting said fraction, and passto the conversion operation the refluxcondensate and unvaporized liquids from said refractionating Zone together with said first men- 15 tioned oil stock, the latter comprising unvaporized portions of said fresh relatively heavy charging stock.

8. A process of treating high boiling point hydrocarbons which comprises subjecting said hy- 20 drocarbons to a relatively high pressure and to a temperature sufficient to effect conversion of at least a portion of said higher boiling point hydrocarbons into lower boiling point hydrocarbons, maintaining said hydrocarbons at said 25' pressure and temperature to effect said conversion, separately withdrawing vapor products from said conversion operation, fractionating the said vapors at a relatively high pressure to condense a portion of said vapors, liquefying and 30 collecting the desired fraction of the remaining vapors, refractionating the reflux condensate produced in said fractionating zone in a separate zone Linder materially reduced pressure to Vaporize a portion of said condensate, preheating 35 fresh relatively heavy charging stock and introducing it into said separate refractionating zone, separately withdrawing residual liquid products from said conversion operation and distilling them to separate a lighter fraction and 40 a heavier fraction, fractionating said lighter fraction in said refractionating zone to remove the desired lower boiling constituents therefrom, condensing vapors issuing from the refractionating Zone to liquefy the desired fraction and 45 collecting said fraction, and passing the condensate produced in the refractionating zone and the said heavier fraction from the residual liquid to said conversion operation together with the said first named high boiling hydrocarbons be- 50 ing charged thereto.

9. A process of treating oils containing high boiling hydrocarbons which comprises subjecting said oil to relatively high pressure and to a temperature sufficient to convert higher boiling Ahy 55 drocarbons into lower boiling hydrocarbons, maintaining said oil at said temperature and pressure to effect said conversion, separately withdrawing vaporous and residual liquid products of said conversion, fractionating said vapors 60 in a zone maintained at relatively high pressure to thereby condense a portion of said vapors, separately withdrawing the fractionated vapors and condensing them, refractionating the reflux condensate from said fractionating zone in a sep- 65 arate combined distilling and fractionating zone maintained at a pressure materially lower than said first mentioned fractionating zone, separately distilling the residual liquid products resulting from said conversion operation by their 70 contained heat, without additional cracking thereof to remove lighter constituents therefrom, fractionating said lighter constituents in said combined distilling and fractionating zone to separate a lighter fraction therefrom, introduc- 75 .ing fresh 'crude' charging stockfinto said combined distilling and fractionating zone, .distilling Vsaid fresh crude stock and fractionatingthe vapors resulting from saidfdistillation to separate lighter constituentsv therefrom, separately removing Afractionated vapors fromrsaid combined .distilling andfractionating zone and condensing them, collecting'in said combined distillingand fractionating zone heavier constituents of said fresh oil together with reflux condensates resultingl from refractionation of said reflux condensate and from fractionating said lighter distilled constituents, and passing the .same as rchargingstock to the aforesaid conversion zone.

10. The process of treating hydrocarbon oil which comprises passing relatively. heavy charging .oil through a heating zone in a stream of restricted cross-sectional area and therein heating said oil to a distilling temperature sufficient to vaporize only part of the desirably light constituents thereof, the amount of heat supplied by the passage of the oil through said heating zone being insuicient for the complete distilling operation desired, introducing the resulting heated oil into a fractional distilling Zone wherein lighter constituents vaporize and are' fractionally condensed to separate, desirably light constituents as vvapors from undesirably heavy constituents as liquid, removing liquid constituents from said distilling zone and passing them through a cracking zone wherein they are raisedV to a crackingtemperature and subjected to con version,y subjecting resulting cracked vapors to vfractionation in a separate fractionating zone to separate desired lightA fractions as vapors from undesirably heavy fractions as reiluxcondensate, said reflux condensate .havingz a temperature `considerably higher than thatofl said heavy Ysuii'icient, toi carry out thel complete operation rst-mentined and heavy fractions of said reflux condensate mingle with heavyfractions of. the heated charging oil, removing light fractionated Vvapors from said fractional distilling zone and condensing them as a desired produca-and pass-y ing heavierconstituents of said reflux condensate faces-,619

to: said :',crackingf'zoneV withisaidheavier liquid constituents.

11.-The:process of treating hydrocarbon oil athat comprises passing charging stock containing crude residual constituents `and lower boiling constituents 'and natural, gasoline fractions through a heating coil to. thereby heat the oil to a. temperature:,fsuiicientv to vaporize a given -fraction,.discharging the heated oil into a dis- ,tillingand fractionating zone wherein vaporiza- .tion takes place zunder approximately atmos- -pheric pressure, fractionating the vapors so evolved ytol separate a distillate comprising natural gasoline fractions,.removing from said distilling and Vfractionating zone the oil thus stripped of itslighter constituents and passing the oil, under superatmospheric pressure, through a coil wherein the oil is heated to a cracking temperature, discharging the heated oil into an Venlarged chamber maintained at a cracking temperature under a relatively high pressure, wherein: conversion of higher boiling oils into lower boiling oils takes place, vpassing evolved vapors into a fractionating column and subjecting them to fractionationztherein, out of .contact with the vapors from said heated charging stock, while still. under pressurek materiallygreater than that .maintained in saidv distilling and fractionating lzone, to form an `overheadvapor fraction and a reflux. condensate, condensing` the overhead vaporzfraction, passing only the reflux condensate into said distilling and fractionating zone to thereby strip therelux condensate of its lower yboiling constituents and combining the heavier portions. thereof -withfthe liquid in said distilling andzffractionatingzone, and withdrawing the combined liquid fromsaid distilling and frac- 'tionating Zone'and passing it to said cracking coilas charging stock.

A312; A Vprocess 'in-.accordance with claim 1l :wherein liquid residue from said enlarged chamber is passed directly,v without'further heating, to a separate`distilling zone wherein a portion :thereof is: vaporizedby :its: contained heat, resulting vapors-being outv of contact with vapors from* saidffheat'ed charging vstock,;1iquefying and :collectingxthe' desired fraction 'offthe vapors so evolved;f'introducing` resulting condensate into lsaid distilling andzfractionatingzone for refractionation, and combining unvaporized constituents thereof with the liquid withdrawn from said zonelast-mentioned"for .passage through said crackingcoil.

" l GUY O. SHEFSTEAD. 

